The present invention relates to a hand-held display apparatus for displaying image information using light sources.
A new information distribution system forms a background for developing this information display apparatus. The new information distribution system is one in which image information contained in a newspaper page produced by a newspaper publishing company (center station) is distributed to homes in various areas throughout a country using a satellite link. The most significant feature of the information distribution system is that the "paper" which has hitherto been a record medium for newspaper information and the like is replaced by electrical data from the beginning of distribution to realize what is called a paperless distribution system. At the same time, fresh newspaper information can be distributed over the whole country by taking advantage of simultaneity and broadcasting which are the greatest merits of the satellite communication.
Since the newspaper information handled by this information distribution system is configured of textual information such as titles, articles and advertisements on the one hand, and figure information such as photographs and illustrations, however, presentation of the newspaper information as dot images involves a vast number of dots. A high dot density is therefore required of display terminals for reproducing the newspaper information. The information display apparatus include, for example, a cold cathode-ray tube (CRT) and a liquid crystal display (LCD). An attempt to display the newspaper information on a CRT or an LCD undesirably increases the size of the apparatus under the circumstances.
In view of this situation, a system using an LED as described in JP-A-2-42476 has recently been closely watched. This is a system in which arbitrary information is emitted in the form of light as linear information from a linear array of LEDs, which linear information is sequentially deflected by a rotary or an oscillational mirror thereby to reproduce the newspaper information. Such a disclosure, however, fails to refer to the case in which a given LED array linearly arranged is visually recognized but suggests a system comprising two LED arrays, one each for the right and left eyes. The visual recognition with the right and left eyes is disclosed in JP-A-4-307590. Specifically, an array of light sources is arranged in the longitudinal direction of the viewer's face, the light emitted by the array of light sources is sequentially reflected in lateral direction by a rotary mirror, and the output light deflected by the rotary mirror is further deflected by a pair of fixed mirrors, one each on right and left sides, for deflecting the light toward the right and left eyes of the viewer. The above-mentioned publication also discloses the technique in which the output of the information display apparatus is deflected in time division by the rotary mirror thereby to display an image corresponding to the right and left eyes.
With the above-mentioned conventional system in which LEDs are visually recognized by right and left eyes, however, an LED array, a magnification lens and a rotary mirror are required to be arranged in a straight line, so that the information display apparatus is undesirably located considerably forward of the viewer. The LED array is also required to be arranged longitudinally of the viewer's face. Further, in the above-mentioned conventional system in which time-division requirement is met by a rotary mirror, displaying an image for the right and left eyes requires a period of time twice as long as normally required, and the displayed image is generally subjected to flickers. In other words, the conventional information display apparatuses are restricted by the size of the existing display elements when a certain degree of dot density is demanded. To meet such a demand, therefore, it is necessary either increase the system size or to employ a complicated structure.